require "zeployment/version"
require "json"

module Zeployment

  def self.number_of_registered_instances_to_loadbalancer (name_of_load_balancer)
    load_balancer_instances_description_hash = get_load_balancer_instances_description(name_of_load_balancer)
    return load_balancer_instances_description_hash["InstanceStates"].length
  end

  def self.get_load_balancer_instances_description (name_of_load_balancer)
    load_balancers_instance_description_command = get_load_balancers_instances_description_command (name_of_load_balancer)
    load_balancer_instances_description = `#{load_balancers_instance_description_command}`
    return JSON.parse(load_balancer_instances_description)
  end


  def self.get_load_balancers_instances_description_command (name_of_load_balancer)
    return "aws elb describe-instance-health --load-balancer-name #{name_of_load_balancer}"
  end

  def self.number_of_instances_in_service (name_of_load_balancer)
    instances_in_service = 0
    load_balancer_instances_description_hash = get_load_balancer_instances_description(name_of_load_balancer)
    load_balancer_instances_description_hash["InstanceStates"].each do |instance_state|
      if instance_state["State"] == "InService"
        instances_in_service = instances_in_service + 1
      end
    end
    return instances_in_service
  end

  def self.number_of_instances_not_in_service (name_of_load_balancer)
    instances_not_in_service = 0
    load_balancer_instances_description_hash = get_load_balancer_instances_description(name_of_load_balancer)
    load_balancer_instances_description_hash["InstanceStates"].each do |instance_state|
      if instance_state["State"] != "InService"
        instances_not_in_service = instances_not_in_service + 1
      end
    end
    return instances_not_in_service
  end

  def self.get_ip_address_of_ec2_from_id (instance_id)
    instance_description_response = `#{get_ip_address_of_ec2_from_id_command(instance_id)}`
    instance_description_hash = JSON.parse(instance_description_response)
    ip_address = instance_description_hash["Reservations"][0]["Instances"][0]["PublicIpAddress"]
    return ip_address
  end

  def self.get_ip_address_of_ec2_from_id_command (instance_id)
    return "aws ec2 describe-instances --instance-id #{instance_id}"
  end

  def self.deregister_instance_from_load_balancer (name_of_load_balancer, instance_id)
    JSON.parse(`aws elb deregister-instances-from-load-balancer --load-balancer-name #{name_of_load_balancer} --instances #{instance_id}`)
  end

  def self.register_instance_with_load_balancer (name_of_load_balancer, instance_id)
    JSON.parse(`aws elb register-instances-with-load-balancer --load-balancer-name #{name_of_load_balancer} --instances #{instance_id}`)
  end

  def self.get_load_balancer_particular_instance_data (name_of_load_balancer, instance_id)
    load_balancers_instance_description_command = "aws elb describe-instance-health --load-balancer-name #{name_of_load_balancer} --instances #{instance_id}"
    load_balancer_instances_description = `#{load_balancers_instance_description_command}`
    return JSON.parse(load_balancer_instances_description)
  end

  def self.instance_is_in_service? (name_of_load_balancer, instance_id)
    load_balancer_insrance_data_hash = get_load_balancer_particular_instance_data name_of_load_balancer, instance_id
    return load_balancer_insrance_data_hash["InstanceStates"][0]["State"] == "InService"
  end

end